Method and armoured power cable for transporting alternate current

Patent metadata

Field	Value
Publication number	US-10438722-B2
Application number	US-201314903647-A
Country	US
Kind code	B2
Filing date	Jul 10, 2013
Priority date	Jul 10, 2013
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

Abstract

A method and armored cable for transporting an alternate current at a maximum allowable working conductor temperature, as determined by the overall cable losses, the overall cable losses including conductor losses and armor losses. The cable includes at least one core, including an electric conductor having a cross section area, and an armor surrounding the core along a circumference. The method includes: causing the armor losses not higher than 40% of the overall cable losses by having the armor made with a layer of a plurality of metal wires having an elongated cross section with a major axis, the major axis being oriented tangentially with respect to the circumference; and transporting the alternate current at the maximum allowable working conductor temperature, in the electric conductor having cross section area sized on the overall cable losses including the armor losses not higher than 40% of the overall cable losses.

First claim

The invention claimed is:

1. A method of transporting an alternate current at a maximum allowable working conductor temperature using an alternate current power cable comprising at least one core, wherein each core comprises an electric conductor having a cross section area and an armour surrounding said core along a circumference, said cable having overall cable losses comprising conductor losses and armour losses, the method comprising:
selecting an armour with armour losses not higher than 10% of the overall cable losses, wherein said armour is made with a layer of a plurality of metal wires having an elongated cross section with a major axis, said major axis being oriented tangentially with respect to the circumference, wherein the layer of the plurality of metal wires includes one or more wires made of a ferromagnetic material, wherein one or more non-ferromagnetic wires are mixed with the one or more wires made of ferromagnetic material in a circumferential direction along the armour's entire length;
modifying a permissible current rating to an increased value, the increased value being determined by the value of the armour losses being not higher than 10% of the overall cable losses; and
transporting at said maximum allowable working conductor temperature in the electric conductor, the alternate current at the increased value of the permissible current rating.

2. The method according to claim 1 , wherein the elongated cross section of the plurality of metal wires of said armour has a ratio between a major axis length and minor axis length at least equal to 1.5.

3. The method according to claim 1 , wherein the elongated cross section of the plurality of metal wires of said armour has a ratio between a major axis length and minor axis length not higher than 5.

4. The method according to claim 1 , wherein the elongated cross section of the plurality of metal wires of said armour has smoothed edges.

5. The method according to claim 1 , wherein the elongated cross section of the plurality of metal wires of said armour has a minor axis from 1 mm to 7 mm long.

6. The method according to claim 1 , wherein the elongated cross section of the plurality of metal wires of said armour has a major axis from 3 mm to 20 mm long.

7. The method according to claim 1 , wherein the alternate current power cable comprises more than one core, and reducing armour losses to a value not higher than 10% of the overall cable losses comprises:
stranding together the cores according to a core stranding lay and a core stranding pitch A; and
winding the plurality of metal wires around the cores according to a helical armour winding lay and an armour winding pitch B, wherein the helical armour winding lay has a same direction as the core stranding lay, and the armour winding pitch B is from 0.4 A to 2.5 A and differs from A by at least 10%.

8. An alternate current power cable comprising:
at least one core comprising an electric conductor; and
an armour surrounding the at least one core along a circumference, in which each electric conductor has a cross section area sized for operating the cable to transport said alternate current at a maximum allowable working conductor temperature, as determined by overall cable losses including armour losses, wherein:
the armour comprises a layer of a plurality of metal wires with an elongated cross section with a major axis, said plurality of metal wires being arranged with the major axis oriented tangentially with respect to the circumference, whereby the armour losses are reduced to a value not higher than 10% of the overall cable losses, wherein the layer of the plurality of metal wires includes one or more wires comprising a ferromagnetic material, wherein one or more non-ferromagnetic wires are mixed with the one or more wires made of ferromagnetic material in a circumferential direction along the armour's entire length; and
further wherein:
the electric conductor has a cross section area sized with a reduced value as determined by reckoning the value of the reduced armour losses not higher than 10% of the overall cable losses; and/or
the alternate current, to be transported in the electric conductor at the maximum allowable working conductor temperature, is sized with an increased value as determined by reckoning the value of the reduced armour losses not higher than 10% of the overall cable losses.

9. The power cable according to claim 8 , wherein the elongated cross section of the plurality of metal wires has a ratio between a major axis length and a minor axis length at least equal to 1.5.

10. The power cable according to claim 8 , wherein the elongated cross section of the plurality of metal wires has a ratio between a major axis length and a minor axis length not higher than 5.

11. The power cable according to claim 8 , wherein the elongated cross section of the plurality of metal wires has smoothed edges.

12. The power cable according to claim 8 , wherein the elongated cross section of the plurality of metal wires has a minor axis from 1 mm to 7 mm long.

13. The power cable according to claim 8 , wherein the elongated cross section of the plurality of metal wires has a major axis from 3 mm to 20 mm long.

14. The power cable according to claim 8 , comprising at least two cores stranded together according to a core stranding lay and a core stranding pitch A, wherein the plurality of metal wires is wound around the at least two cores according to a helical armour winding lay and an armour winding pitch B, wherein the helical armour winding lay has a same direction as the core stranding lay, and the armour winding pitch B is from 0.4 A to 2.5 A and differs from A by at least 10%.

15. A method of transporting an alternate current at a maximum allowable working conductor temperature using an alternate current power cable comprising at least one core, wherein each core comprises an electric conductor having a cross section area and an armour surrounding said core along a circumference and the cable having overall cable losses comprising conductor losses and armour losses, the method comprising:
selecting an armour with armour losses not higher than 10% of the overall cable losses, wherein the armour is made with a layer of a plurality of metal wires having an elongated cross section with a major axis, the major axis being oriented tangentially with respect to the circumference, wherein the layer of the plurality of metal wires includes one or more wires made of a ferromagnetic material, wherein one or more non-ferromagnetic wires are mixed with the one or more wires made of ferromagnetic material in a circumferential direction along the armour's entire length;
sizing the electric conductor with a reduced conductor cross section area determined by the value of the armour losses being not higher than 10% of the overall cable losses; and
transporting, at the maximum allowable working conductor temperature in the electric conductor, the alternate current.

16. A method of transporting an alternate current at a maximum allowable working conductor temperature using an alternate current power cable comprising at least one core, wherein each core comprises an electric conductor having a cross section area and an armour surrounding said core along a circumference, said cable having overall cable losses comprising conductor losses and armour losses, the method comprising:
selecting an armour with armour losses not higher than 10% of the overall cable losses, wherein said armour is made with a layer of a plurality of metal wires having an elongated cross section with a major axis, said major

Assignees

• Prysmian Spa

Inventors

• Maioli Paolo
• Bechis Massimo

Classifications

• H01B7/14

  Submarine cables · CPC title

• H01B7/26 Primary

  Reduction of losses in sheaths or armouring · CPC title

• H01B7/04

  Flexible cables, conductors, or cords, e.g. trailing cables · CPC title

• H01B13/02

  Stranding-up · CPC title

• H01B9/025

  composed of helicoidally wound wire-conductors · CPC title